Odd bug regarding types in member expressions.

[7ombie]

There are some cases where the types (MemoryLayout and Float) are not highlighted as types in the following expression:

MemoryLayout<Float>.stride

In other (most) cases, the types are highlighted correctly. The simplest (and oddest) example I could find was the following:

let a = MemoryLayout<Float>.stride
let b = MemoryLayout<Float>.stride + 1

In the first line, the types are not highlighted, while on the second line they are.

Note: I'm working with Helix (trying to update their Swift support), and came across this issue there. I'm assuming it's upstream, as their highlights.scm file is not very different from yours (despite being well over a year out of sync).

[alex-pinkus]

This is odd indeed. I’m going to baselessly speculate that we’re parsing as (MemoryLayout < Float) > (.stride) (i.e. comparison operators). I have to think a bit about how we would restructure the precedence to handle that properly.

[7ombie]

Thanks for looking into it for us. It's not urgent. Just bringing it to your attention really.

Thanks for all your hard work. Much appreciated.

[bbb651]

I asked a question regarding this on the swift forums and got a very helpful response, linking me to this function that does a lookahead to decide if it can parse it as a generic arguments list, it first parses the generic arguments list and does checks for the next token:

extension Lexer.Lexeme {
  var isGenericTypeDisambiguatingToken: Bool {
    switch self.rawTokenKind {
    case .rightParen,
      .rightSquare,
      .leftBrace,
      .rightBrace,
      .period,
      .comma,
      .semicolon,
      .endOfFile,
      .exclamationMark,
      .postfixQuestionMark,
      .colon:
      return true
    case .binaryOperator:
      return self.tokenText == "&"
    case .postfixOperator:
      return false
    case .leftParen, .leftSquare:
      // These only apply to the generic type if they don't start a new line.
      return !self.isAtStartOfLine
    default:
      return false
    }
  }
}